Ball Screw Lubrication Channels to Eliminate Dead Volumes
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Solution Overview
Problem
Ball screw assemblies require frequent lubrication due to the presence of dead volumes that do not contribute effectively to lubrication, leading to increased maintenance and reduced efficiency.
Innovation Solution
A ball screw design with alpha and beta lubricant channels and a shuttle mechanism that promotes a recirculating lubricant flow path, minimizing dead volumes and enhancing lubrication by depositing lubricant further along the load circuits, utilizing check valves to control flow direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional lubrication channels are used in ball screw assemblies, then lubricant can be introduced into the closed channel and ball return channel, but dead volumes remain that do not contribute effectively to lubrication, requiring frequent maintenance and refilling
Solution Approach 1:
The lubrication system is segmented into multiple independent channels (first lubricant channel and second lubricant channel) that are spatially separated and functionally distinct. Each channel serves a specific portion of the load circuit, eliminating dead volumes by ensuring complete lubricant coverage throughout the ball screw assembly.
Solution Approach 2:
The lubricant channels are positioned at different radial distances from the central axis of the screw shaft. The first lubricant channel is at a first radial distance while the second lubricant channel is at a second radial distance, creating a multi-dimensional lubrication distribution system that eliminates blind spots and dead volumes.
2Duration of action of moving object
If multiple lubricant channels are introduced at different radial distances, then dead volumes are eliminated and lubrication is improved, but the device complexity increases
Solution Approach 1:
The multiple lubricant channels work together as an integrated system to provide comprehensive lubrication coverage. Each channel contributes to the overall lubrication function, with the first channel serving one region and the second channel serving another region, collectively eliminating dead volumes and extending lubrication intervals without requiring overly complex individual channel designs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design extends lubrication intervals and improves the efficiency and service life of ball screw assemblies by ensuring consistent lubrication without dead volumes, reducing maintenance needs.
Implementation Method 1
The relative rotational motion is converted to relative longitudinal motion or relative longitudinal motion is converted to relative rotational motion via a plurality of ball bearings that interact with both the screw shaft and the ball nut
Implementation Method 2
lubricant such as oil or grease is typically introduced into one or more of the closed channel or raceway and ball return channel through an oil or grease hole
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A ball screw (2) comprising a screw shaft (4), a ball nut (6), and alpha and beta load circuits (42, 50) are disclosed. The alpha and beta load circuits each comprise first and second parts. The screw shaft is longitudinally extending with a longitudinal central axis (A) and at least part of the longitudinally extending surface of the screw shaft comprises an external thread (8), and at least one of the first parts of the alpha and beta load circuits comprise a part of the external thread. The ball nut comprises a body (10), a bore (12), the second parts of the alpha and beta load circuits, and an alpha and a beta lubricant channel (64, 76). The bore is defined by the body, is longitudinally extending with a longitudinal central axis (A) , has a first and second end, and has at least one longitudinally extending surface (18) extending between the first and second ends. The first and second ends of the bore each comprise a mouth (30, 36), and each mouth opens through an outside surface of the body. The longitudinally extending surface of the bore comprises at least one internal thread (40A, 40B), and the second parts of the alpha and beta load circuits comprise at least a part of an internal thread. The screw shaft extends through the bore of the ball nut and the screw shaft and bore are so configured that they are coaxial. The external thread and each internal tread are so configured that the external thread and at least one of the internal threads together define at least one of a portion of the alpha load circuit and a portion of the beta load circuit. The alpha load circuit is spaced from the first end of the bore and extends an axial distance along the bore, and the beta load circuit is spaced from the second end of the bore and extends an axial distance along the bore. The alpha and beta load circuits are spaced from each other. The alpha lubricant channel comprises a first and a second channel end (68, 70) and a flow path (66) between the first and second channel ends. The first channel end is located between the first end of the bore and the second part of the alpha load circuit, and the second channel end is located between the second part of the alpha load circuit and the second part of the beta load circuit. The beta lubricant channel comprises a first and a second channel end (80, 82) and a flow path (78) between the first and second channel ends. The first channel end is located between the second end of the bore and the second part of the beta load circuit, and the second channel end is located between the second part of the alpha load circuit and the second part of the beta load circuit. Rotation of one of the screw shaft and the ball nut relative to the other around the longitudinal axis causes axial movement of the ball nut relative to the screw shaft. The ball screw further comprises a shuttle (58). The shuttle is engaged with the longitudinally extending surface of the screw shaft, the shuttle is located between the first parts of the alpha and beta load circuits, and the shuttle is in sliding contact with the ball nut. Rotation of one of the screw shaft and the ball nut relative to the other around the longitudinal axis drives lubricant through one of the alpha and beta lubricant channels.